Impact of topsoil compaction on crop and pasture yield under varying climates and soil textures: A data synthesis

Soil compaction caused by machinery traffic or livestock grazing typically reduces crop and pasture yields, lowering farmer incomes while increasing input costs for tillage, irrigation, and nutrients. However, few studies have quantified how yield responses to compaction vary across soil textures and climates. Here we synthesise published data to quantify the relationships between yield and soil physical indicators, and to evaluate the moderating roles of soil texture and climate. We extracted yield responses to bulk density (BD) and degree of compaction (DoC) from the literature and conducted a global synthesis using main-effect regression models. Across studies, yield responses followed two dominant patterns: a negative linear decline with increasing BD or DoC, or a quadratic response with yields increasing to an optimum and then declining. For quadratic relationships, coarse-textured soils tended to show a higher optimum BD but a lower optimum DoC than fine-textured soils. Dry climates tended to show a higher optimum BD and a lower optimum DoC than wet climates. Beyond the optimum, whether inferred from linear or quadratic relationships, wet conditions had a less negative yield–DoC slope than in dry conditions, suggesting greater vulnerability to compaction in drier climates once critical thresholds are exceeded. Knowledge gaps include the lack of studies relating pastoral and many crop responses specifically to dynamic structural values (e.g., air capacity, available water capacity, penetration resistance, and aggregate stability) across textures and climates.